The objective of this research is to elucidate the genetic and hormonal regulatory realization of enzymes in developing brain. We have concentrated our study on the enzyme L-glycerol-3-P dehydrogenase (EC 1.1.1.8). This enzyme possess two isozymic forms, one expressed in the embryo, the other expresed in adult. By analyzing the molecular mechanisms controlling the transition from one isozyme to the other, an understanding of mechanisms controlling development can be achieved. These investigations are facilitated by the fact that the transition from the embryonic to adult isozyme occurs in vitro in reaggregating cell cultures of mouse nerve cells. This tissue culture system will allow us to assess whether factors such as cell to cell interactions or hormones are critical in determining the expression of specific genes during development, or whether intrinsic timing mechanisms control most features of the development expression of L-glycerol-3-P dehydrogenase. BIBLIOGRAPHIC REFERENCE: Kozak, L.P., and K.J. Erdelsky. 1975. The genetics and developmental regulation of l-glycerol 3-phosphate dehydrogenase. J.Cell. Physiol. 85:437-448.